2.) Create a list of everything you need to do, then start to work through it.
a.) Have a conversation with your wife. Inform her about what's happening, what issues you're facing, and ask her about her thoughts. Get on the same page, that way there are two of you working through this. What's her game plan? She'll likely have some action items that should go onto your list.
Get your emotions out, but then move on. I've been doing the startup thing for 14+ years and married for 8+. I cannot emphasize enough that you should not overburden your spouse. She's got a lot on her plate now, so get your emotions out once (if you're into that), then stay upbeat.
b.) Schedule a meeting with your investors. Have a set agenda, use a PowerPoint (or other presentation software) that outlines your current status, etc. Also, show that you are a professional by showing them you have a plan/budget/timeline to shutdown the business.
Your investors are professionals. They know that a large percent of early startups fail. What they will want from your is professionalism.
Also, ask for their input. What do they need you to do?
c.) Legal: Speak with your attorney (this can also be before #b). Get their input on your legal checklist.
You must shutdown the business correctly. Your attorney will be a big asset. Keep your meeting with them professional and focused. Don't waste time on emotions in this meeting.
d.) Schedule a team meeting and speak with your employees. Help them transition if you can. If you're overwhelmed, which it sounds like, then tell them you'll be happy to give glowing references. This is easy and will require minimal work on your part while keeping the relationship alive.
As with #a, don't overburden your employees with your emotions. Sorry, but complaints flow up, not down. They will have their own pressures, and your job as a manager is to help assuage their fears and help them see that everything will be ok.
e.) It sounds like you don't have kids. Yah! Seriously, grab a beer. This is so much easier without kids.
f.) Fill-in this list with input from everyone above plus your co-founders.
g.)It's only Tuesday. Get moving and this done before the weekend.
3.) Debt: To any first time founders, please allocate budget to shutting down a business. Experience matters here, and it's best practice to know your shutdown costs, to budget for them, and to have the professionalism to shut the business down when you have just enough money to close up shop. You should pay debts, invoices that are due, employee salaries, legal fees to shutdown, etc.
To the OP, create a list of assets/liabilities. If you can sell assets to pay for liabilities then do it. Be cool about who you owe money to. If these are other small businesses / startups, then try to make your debt whole.